Ink-jet recording system

ABSTRACT

There is disclosed ink-jet recording process for carrying out a recording by adhering ink droplets on a recording medium, wherein the recording is carried out under the condition that the ink is adhered in an amount ranging between 3.0×10 5  pl/cm 2  and 3.0×10 6  pl/cm 2  in solid image recording when the recording is carried out with a recording density of 10 dots/mm×10 dots/mm or more.

This application is a continuation of application Ser. No. 07/136,716filed Dec. 22, 1987, now abandoned.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an ink-jet recording process forrecording information such as images, letters and symbols on paper,light-transmissive recording medium or the like using an ink-jetrecording apparatus.

2. Related Background Art

Ink-jet recording is known as a superior recording method which is notparticularly demanding in choice of recording mediums, and so researchand development have been extensively made on recording apparatus,recording processes and recording mediums.

However, in the ink-jet recording apparatus developed and madecommercially available, it has actually been impossible tosimultaneously obtain;

(i) a recorded image having a high optical density (OD);

(ii) a recorded image which is good in print quality and free from anyfeathering on the peripheral part of letters or images; and

(iii) a good drying time characteristic;

unless there are used recording mediums developed for exclusive use inan ink-jet recording which are called ink-jet recording paper or ink-jetrecording transparenty films.

The above performances (i) to (iii) can not be simultaneously satisfiedwhen recording is carried out on recording media such as paper includingelectrophotographic recording paper (PPC paper), letter paper, bondpaper, post cards, writing paper, envelopes, report paper, etc.generally used in offices, homes, etc. and transparent films (OHP films)with use of conventionally known ink-jet recording apparatus. Even whenan ink-jet recording paper is used, there has also been accompanied withthe disadvantage such that recording can not be performed on both sidesthereof since most ink-jet recording paper is only a one-side coatedpaper, and thus the grade of prints and the drying time characteristicmay be lowered if recording is carried out on the side on which nocoating was applied. Thus, various developments have been made for thepurpose of obtaining recorded images;

(i) which are not particular in choice of recording faces (or are notparticular in choice of materials such as paper or films and of thereverse side or obverse side thereof);

(ii) which have a high optical density;

(iii) which are good in print quality and free from feathering; and

(iv) which have a good drying time characteristic; and there have beendeveloped (1) a process in which recording is carried out using astrongly alkaline ink of about pH 13 (Japanese Laid-Open PatentApplication No. 102970/1982) and (2) a process in which recording iscarried out using an ink-jet recording apparatus of a continuous typesuch as a charge-controlled type, etc.

However, it is known in the process of (1) that an ink so stronglyalkaline can be dangerous to handle, that although good printing can beperformed on acidic sized paper employing rosin or the like, there areposed the disadvantages such that both drying time characteristic andquality of prints may be greatly lowered when there is used neutralpaper employing an alkyl ketone dimer or the like, and also thatstrike-through tends to occur probably because of large permeability ofthe ink into the paper.

In the process of the above (2), although it is a process that canachieve a recording of a relatively high density, there are limitationsin the precision of the nozzles from which an ink is ejected, and thusfine ink droplets can be stably ejected only with difficulty. As aresult, unless the recording density is controlled to substantially nomore than about 9.5 dots/mm (240 dots/inch), the drying timecharacteristic may be lowered (i.e., the recording surface may be soiledwhen smeared with fingers) and the irregular spreading of dots(feathering) may occur, because of an overly large amount of the ink tobe fixed on the recording face, so that there is obtained a low printquality, i.e., a recorded image having blurred peripheral parts.

With the recording density of about 9.5 dots/mm, there have beenaccompanied with the disadvantages such that it is impossible to carryout sharp printing for close (or tight) chinese characters (such as " ")or sometimes difficult to carry out the recording that can be smooth andnatural in oblique line part or curved line part such as "/", " " or"O", and every dot can be visually observed, giving recorded images ofconspicuous ruggedness and lower grade.

The prior art includes the following documents relating to thebelow-listed ink-jet recording conditions:

1. Amount of ink adherence per unit area.

Itoh et al., "High Optical Density Recording Paper for Ink-JetPrinting," National Technical Report, Vol. 28, No. 6, Dec. 1982,discusses ejecting different amounts of ink and evaluating recordingquality, as pointed out in Table 2 (which discloses ejecting up to 9.4pl/cm² of ink) and FIG. 2b (which shows a pattern printed at 2lines/mm);

U.S. Pat. No. 4,503,111 discusses recording with ink coverage at 1.5μl/cm² (column 5, lines 1-3; see also column 6, lines 61-63); and

Japanese Laid-Open Patent Application No. 60-172582 discloses that themaximum amount of ink applied to recording paper is 3.5 mg/cm², which,if the specific gravity of the ink is assumed to be 1.0, is 3.5×10⁶pl/cm².

2. Concentration of colorants in inks.

U.S. Pat. No. 4,381,946 discloses dye concentration in inks of 0.5% to8% by weight (column 4, line 8-18); and

U.S. Pat. No. 4,295,889 discloses dye concentrations in inks of 0.1% to20% by weight (column 4, lines 44-48).

3. Paper basis weight.

U.S. Pat. No. 4,440,827 discloses recording paper with a basis weight of70 to 83 g/m² (columns 6 and 8, Tables 1 and 9);

U.S. Pat. No. 4,478,910 describes recording paper with a basis weight of60 to 85 g/m² (columns 4-6, Tables 1 and 2); and

European Patent Application 174,859 discloses recording paper with abasis weight of 50 to 90 g/m² having an ink acceptor layer.

4. Ink solvent boiling point.

U.S. Pat. No. 4,295,889 (see No. 2 above) discloses the followingsolvents for inks, which have the following boiling points:

    ______________________________________                                        Solvent               Boiling Point (°C.)                              ______________________________________                                        Methyl alcohol        64.5                                                    Ethyl alcohol         78                                                      n-Propyl alcohol      97                                                      iso-Propyl alcohol    82.7                                                    n-Butyl alcohol       118                                                     sec-Butyl alcohol     98.5                                                    tert-Butyl alcohol    82.5                                                    iso-Butyl alcohol     108                                                     Dimethylformamide     153                                                     Dimethylacetamide     165                                                     Acetone               56.5                                                    Diacetone alcohol     167.9                                                   Tetrahydrofuran       64-65                                                   Dioxane               101                                                     Polyethylene glycol   >300                                                    Polypropylene glycol  >300                                                    Ethylene glycol       197                                                     Propylene glycol      188.2                                                   Butylene glycol       190.5                                                   Triethylene glycol    179                                                     Thiodiglycol          282                                                     Hexylene glycol       197                                                     Diethylene glycol     245                                                     Glycerol              290                                                     Ethylene glycol methyl ether                                                                        124.5                                                   Diethylene glycol methyl ether                                                                      194.2                                                   Diethylene glycol ethyl ether                                                                       195                                                     Triethylene glycol monomethyl ether                                                                 249                                                     N-Methyl-2-pyrrolidone                                                                              202                                                     1,3-Dimethyl-2-imidazolinone                                                                        226.                                                    ______________________________________                                    

SUMMARY OF THE INVENTION

Accordingly, an object of the present invention is to provide an ink-jetrecording process capable of performing a recording;

(i) which is not especially particular in choice of recording faces (oris not particular in choice of materials such as paper or films and ofthe reverse side or obverse side thereof);

(ii) which achieves a high optical density;

(iii) which is good in print quality and free from feathering; and

(iv) which achieves a good drying time characteristic;

A further object of the present invention is to provide an ink-jetrecording process which can smoothly and naturally reproduce acomplicated chinese character / or an oblique or curved line part of animage.

The above objects can be achieved by the present invention as describedbelow.

The present invention is to provide an ink-jet recording process forrecording by adhering ink droplets on a recording medium, wherein ink isadhered in an amount ranging between 3.0×10⁵ pl/cm² and 3.0×10⁶ pl/cm²in solid image recording at a recording density of 10 dots/mm×10 dots/mmor more.

In another embodiment of the present invention, there is provided anink-jet recording process for recording by adhering ink droplets on arecording medium, wherein ink is adhered in an amount ranging between1.0×10⁶ pl/cm² and 2.0×10⁶ pl/cm² in solid image recording with arecording density of 14 dots/mm×14 dots/mm or more.

In a further embodiment of the present invention, there is provided anink-jet recording process for recording by adhering ink droplets on arecording medium, wherein said ink contains 1 to 45% by weight of anorganic solvent having a boiling point of 150° C. or more, and the inkis adhered in an amount ranging between 3.0×10⁵ pl/cm² and 3.0×10⁶pl/cm² in solid image recording with a recording density of 10dots/mm×10 dots/mm or more.

In a still further embodiment of the present invention, there isprovided an ink-jet recording process for recording by adhering inkdroplets on a recording medium, wherein said ink contains 1 to 45% byweight of an organic solvent having a boiling point of 150° C. or more,and the ink is adhered in an amount ranging between 1.0×10⁶ pl/cm² and2.0×10⁶ pl/cm² in solid image recording with a recording density of 14dots/mm×14 dots/mm or more.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

A first feature of the present invention is to use an ink-jet recordingapparatus with a recording density of 10 dots/mm×10 dots/mm(length×width) or more.

This is based on the fact that the present inventors have researched andstudied on the relationship between the recording density and the"looks" and have found that the curved line part and the oblique linepart appear to be smooth and natural in feeling if the recording densityis 10 dots/mm×10 dots/mm or more.

In the case that a recording density is at a level as low as about 8dots/mm×8 dots/mm or less, the size of every dot is so large that theabnormality such as white-spotting, color non-uniformity or densitynon-uniformity tended to become conspicuous if mis-direction of inkejection occur for some reason (for example, because of dust sticking toa part of the nozzles).

In contrast thereto, it was also found that with a recording density of10 dots/mm×10 dots/mm or more, the dot is originally so small that suchabnormality favorably becomes hardly conspicuous since only a verynarrow streak (white-spotting), or non-uniformity in color or densitywas produced even when the misdirection of ejection occurred.

In the case when recording was carried out with a recording density ofabout 4 to 8 dots/mm×4 to 8 dots/mm and using ink droplets of largesize, it was further found that ink droplets impinge on the recordingface before previously impinged droplets permeate into the recordingface when the succeeding ink droplets are immediately follow the earlierink droplets face, so that the ink is splashed around the dots at thepart which overlap, and soil the recording face.

In the present invention, recording can be satisfactorily performed whena recording density is in the range of 10 dots/mm×10 dots/mm or more,preferably in the range of from 10 dots/mm×10 dots/mm to 24 dots/mm×24dots/mm, more preferably in the range of from 14 dots/mm×14 dots/mm to24 dots/mm×24 dots/mm.

In the present invention, recording can also be satisfactorily performedemploying the on-demand system with multi-nozzles.

The function of the multi-nozzles herein mentioned is that a pluralityof nozzles are used for forming one image and adjacent dots aresubstantially applied in printing simultaneously.

A second feature of the present invention resides in the range of theamount of the ink to be adhered on the recording face.

More specifically, all of the objects of the present invention can besatisfied at the same time by setting to a given range the amount of theink to be adhered on the recording face.

If the ink is adhered in a smaller amount, a colorant on the recordingface can be present only in a smaller quantity, bringing about thedisadvantage that the optical density of recorded images decreases togive unsharp recorded images having the impression that they are faintas a whole.

If a concentration of the dye in the ink is set to be 10% by weight ormore, a sufficient OD value can be attained, but in recording apparatushaving multi-nozzles, a nozzle or nozzles not in use for recording maybe clogged with the ink, resulting in uselessness in practical purposes.

However, if ink is adhered on the recording face in a greater amount,the drying time characteristic tends to be extremely lowered under theconditions shown below, even if the colorant is contained in the ink ina decreased amount for example;

(i) under the condition of a high humidity atmosphere:

(Drying time characteristic is lowered because the recording medium hasabsorbed moisture and also components in an ink evaporate slower fromthe surface of the recording medium.)

(ii) under the condition of a low temperature:

(It is lowered because medium components in an ink evaporate slower ifan atmospheric temperature is low.)

(iii) in the case that recording is performed on strongly size paper:

(Since sizing is applied so as to prevent the feathering, it takes along time for an ink to permeate into the inside of the paper.Therefore, drying time characteristic is lowered.)

When the ink is adhered on the recording face in a greater amount andalso the colorant is contained in a greater amount, there is also posedthe disadvantage that the recorded images may be extremely soiled ifthey are smeared with sweaty fingers or the like.

Now, to achieve the objects of the present invention, the presentinventors have studied under the varied conditions regarding the amountof the ink to be adhered on the recording face. As a result, they foundthat the recording may preferably be carried out under the conditionthat the amount ranges preferably between 3.0×10⁵ pl/cm² and 3.0×10⁶pl/cm², more preferably between 5.0×10⁵ pl/cm² and 2.5×10⁶ pl/cm², andmost preferably between 1.0×10⁶ pl/cm² and 2.0×10⁶ pl/cm², in solidimage recording, and thus reached the present invention.

Also in the case that color-mixed areas are formed on a recording mediumwith use of two or more kinds of inks of different colors as in a colorprinter, recording may preferably be carried out using the ink rangesdescribed above.

For example, in the case that a yellow area is formed on the recordingmedium with use of yellow ink and a green area is formed by overlappingcyan ink on it, if follows that the ink is adhered on the recordingmedium in an amount twice the amount used in the instance of themonochrome. Thus, the amount of the ink to be adhered at the color mixedareas is required to be controlled within the range described above.

To described an ink used in the present invention, various dyes andcolorants can be used as coloring matters, and the type amount thereofmay be selected depending on what purposes they will be used for andalso taking account of the clogging of nozzles and so forth.

As for a concentration of the dye, it can be suitably used in the rangeof 0.5 to 10.0% by weight, preferably in the range of 1.0 to 5.0% byweight, and more preferably in the range of 1.0 to 3.0% by weight basedon the total amount of the ink, taking account of the optical density ofrecorded images.

A liquid medium for dissolving or dispersing the colorant may be any ofaqueous systems in which water and water-soluble organic solvents suchas glycols and glycol ethers are used in combination and non-aqueoussystems containing aromatic type, aliphatic type, ester type or ethertype water-insoluble organic solvents. However, taking account of thesafety, smell, strike-through of paper, etc., aqueous systems arepreferred.

The present inventors have further studied an organic solvent containedin the ink. As a result, they found that better results can be obtainedwhen the ink contains 1 to 45% by weight of an organic solvent having aboiling point of 150° C. or more.

If the organic solvent having a boiling point of 150° C. or more, amongthe organic solvents contained in the ink, is contained in the amountmore than 45% by weight, it tends to take a long time for the solvent toevaporate from or to permeate into the recording face, so that thedrying time characteristic is lowered.

It was also confirmed that, particularly in respect of an organicsolvent having a boiling point of 300° C. or more, if contained in theink in an amount of 10% by weight or more, the drying time tends to belowered and the ink tends to permeate into the recording medium slowereven when the remaining part of the ink is constituted only by solventhaving a boiling point of 150° C. or less such as water, alcohol andaliphatic hydrocarbons, so that the "whiskers" called feathering arelikely to appear, making it impossible to obtain excellent images andgood print quality.

The organic solvent having a boiling point of 150° C. or more may becontained more preferably in the range of from 1 to 30% by weight, stillmore preferably in the range of from 1 to 25% by weight, and mostpreferably in the range of from 5 to 20% by weight. In respect of theorganic solvent having a boiling point of 300° C. or more, it may becontained more preferably in the range of 5% by weight or less.

With regard to the organic solvent having a boiling point of 150° C. ormore, the dry time characteristic is considered of common knowledge, toimprove as the solvent is contained in a smaller amount, although not ifthe solvent is contained in an overly small amount. Thus, it maydesirably be contained in an amount of 1% by weight or more, preferably5% by weight or more.

The recording medium to be used may be any of coated paper and ordinarypaper, but particularly effective for the present invention is paperhaving a basis weight in the range of from 45 to 200 g/m².

The amount of ink to be adhered (pl/cm²), as used in the presentinvention, can be readily determined by any of the methods in which;

(1) it is determined from the decreased amount, measured after solidimage recording, of the ink in an ink tank connected to nozzles, and thearea of the solid image recording; and

(2) it is determined from the amount of the ink ejected from one nozzleaccording to one signal, and the recording density.

The present invention will be described in greater detail by thefollowing Examples and Comparative Examples.

EXAMPLE 1

Prepared was ink having the following composition.

    ______________________________________                                        C.I. Direct Black 62   3.0    wt. %                                           Ethanol (b.p. 78° C.)                                                                         0.5    wt. %                                           Ethylene glycol (b.p. 197° C.)                                                                20.0   wt. %                                           Diethylene glycol (b.p. 245° C.)                                                              5.0    wt. %                                           Water                  71.5   wt. %                                           ______________________________________                                    

Using this ink and an ink-jet recording apparatus having a multi-nozzleon-demand type head having 48 nozzles, ink-jet recording was performedat a recording density of 14.2 dots/mm×14.2 dots/mm (360 dots/inch×360dots/inch) on the five kinds of paper (A) to (E) shown below under thesolid image recording condition such that the volume of ink ejected fromone nozzle according to one signal was 58 pl, in other words, the inkwas adhered on the recording face in an amount of 1.2×10⁶ pl/cm².

As a result, the resulting recorded images had an optical density (OD)of 1.2 in an average value.

The drying time (the shortest time by which the recorded images are notsoiled if they are smeared with filter paper) under 80% RH at 15° C. wasalso found to be 52 seconds in an average value; and the drying timeunder 55% RH at 20° C., 41 seconds in an average value.

The looks of recorded images were overall evaluated by 10 panelists inrespect of optical density, grade, presence of feathering, andreproducibility of an image at an oblique-line part and a curved linepart thereof, to find that the five rank evaluation (5: very good . . .1: very poor) was 4.2 in an average value, showing a good result.

Ink-jet recording was also performed according to the process of thepresent invention on a transparent film comprising a polyester filmcoated with a mixture of polyvinyl alcohol and polyvinyl pyrrolidone. Asa result, there were obtained good recorded images. Paper for recordedimage evaluation:

(A): Canon Paper NP-DRY (available from Canon Inc.; PPC paper)

(B): Xerox 4024 DP (available from Xerox Corp.; PPC paper)

(C): Hammermill Bond (available from Hammermill paper Corp.; bond paper)

(D): Gilbert Bond (available from Mead Corp.; bond paper)

(E): New OK (available from Oji Paper Co., Ltd.; wood free paper)

EXAMPLES 2 TO 9

Using the inks having the composition shown below in (2) to (9),recordings were performed in the same manner as in Example 1 but underthe conditions as shown in Table 1. As a result, there were obtainedgood results in all, as shown in Table 2.

    ______________________________________                                        (2):                                                                          C.I. Food Black 2        1.4    wt. %                                         C.I. Direct Yellow 86    0.1    wt. %                                         Diethylene glycol        8.0    wt. %                                         n-Propyl alcohol (b.p. 97° C.)                                                                  5.0    wt. %                                         Water                    85.5   wt. %                                         (3):                                                                          C.I. Acid Black 52       2.5    wt. %                                         Glycerol (b.p. 290° C.)                                                                         17.5   wt. %                                         Ethylene glycol          5.0    wt. %                                         Methanol (b.p. 64.5° C.)                                                                        4.0    wt. %                                         Water                    71.0   wt. %                                         (4):                                                                          C.I. Direct Blue 199     2.0    wt. %                                         Diethylene glycol        15.0   wt. %                                         n-Butanol (b.p. 118° C.)                                                                        1.0    wt. %                                         Water                    82.0   wt. %                                         (5):                                                                          C.I. Direct Black 154    2.0    wt. %                                         Thiodiethanol (b.p. 282° C.)                                                                    14.0   wt. %                                         Glycerol                 6.0    wt. %                                         Ethanol                  4.0    wt. %                                         Water                    74.0   wt. %                                         (6):                                                                          C.I. Acid Red 8          5.0    wt. %                                         Polyethylene glycol 200 (b.p. > 300° C.)                                                        3.0    wt. %                                         Ethylene glycol          30.0   wt. %                                         Water                    62.0   wt. %                                         (7):                                                                          C.I. Food Black 2        1.4    wt. %                                         C.I. Direct Yellow 86    0.1    wt. %                                         Glycerol                 10.0   wt. %                                         Thiodiethanol            10.0   wt. %                                         Water                    78.5   wt. %                                         (8):                                                                          C.I. Solvent Black 29    1.0    wt. %                                         Benzyl alcohol (b.p. 205° C.)                                                                   20.0   wt. %                                         Methyl cellosolve (b.p. 125° C.)                                                                10.0   wt. %                                         Ethanol                  69.0   wt. %                                         (9):                                                                          C.I. Food Black 2        2.6    wt. %                                         C.I. Direct Red 227      0.2    wt. %                                         C.I. Direct Yellow 86    0.2    wt. %                                         Diethylene glycol        11.0   wt. %                                         Ethylene glycol          5.0    wt. %                                         Ethanol                  3.0    wt. %                                         Water                    78.0   wt. %                                         ______________________________________                                    

EXAMPLES 10 AND 11

Using ink having the same composition as in Example 9, recording wasperformed in the same manner as in Example 1 but under the conditions asshown in Table 1. As a result, there were obtained good results in all,as shown in Table 2.

EXAMPLE 12

Prepared were ink (Y) and ink (C) of the following composition.

    ______________________________________                                        Ink (Y):                                                                      C.I. Direct Yellow 86 1.5    wt. %                                            Diethylene glycol     20.0   wt. %                                            Ethanol               5.0    wt. %                                            Water                 73.5   wt. %                                            Ink (C):                                                                      C.I. Direct Blue 199  2.5    wt. %                                            Diethylene glycol     20.0   wt. %                                            Ethanol               5.0    wt. %                                            Water                 72.5   wt. %                                            ______________________________________                                    

Using ink (Y) and ink (C) and also using an ink jet recording apparatushaving two multi-nozzle on-demand type heads each having a nozzle numberof 256, ink jet recording for green images was peformed at a recordingdensity of 15.7 dots/mm×15.7 dots/mm (400 dots/inch×400 dots/inch) onthe five kinds of paper (A) to (E) shown in Example 1 by making a printin an overlapping fashion under the solid image recording condition suchthat the volume of ink ejected from one nozzle in each head according toone signal was 35 pl, in other words, the ink was adhered on therecording face in an amount of 1.7×10⁶ pl/cm² as a result.

As a result, the resulting recorded images had an optical density (OD)of 1.3 in an average value.

The drying time under 80% RH at 15° C. was also found to be 47 seconds;and under 55% RH at 20° C., 32 seconds; both in average values.

The overall evaluation point was 4.2, showing good results.

COMPARATIVE EXAMPLES 1 AND 2

Using the ink having the following composition, the recording wascarried out in the same manner as in Example 1 but under the conditionsas shown in Table 1. Results obtained are shown in Table 2.

    ______________________________________                                        C.I. Food Black 2      1.9    wt. %                                           C.I. Direct Yellow 86  0.1    wt. %                                           Glycerol               15.0   wt. %                                           Triethylene glycol (b.p. 288° C.)                                                             8.0    wt. %                                           Water                  75.0   wt. %                                           ______________________________________                                    

COMPARATIVE EXAMPLES 3 AND 4

Using the ink having the following composition, the recording wascarried out in the same manner as in Example 1 but under the conditionsas shown in Table 1. The results obtained are shown in Table 2.

    ______________________________________                                        C.I. Food Black 2     2.9    wt. %                                            C.I. Direct Yellow 86 0.1    wt. %                                            Ethylene glycol       5.0    wt. %                                            Diethylene glycol     10.0   wt. %                                            Ethanol               2.0    wt. %                                            Water                 70.0   wt. %                                            ______________________________________                                    

                  TABLE 1                                                         ______________________________________                                                                  *2      *3                                                            Noz-    Ink     Amount of                                                     zle     vol-    ink adher-                                  Recording density num-    ume     ed                                          dots/mm.sup.2 (DPI).sup.*1                                                                      ber     (pl)    (pl/cm.sup.2)                               ______________________________________                                        Examples:                                                                      2   11.8 × 11.8 (300 × 300)                                                            50      51    7.1 × 10.sup.5                       3   15.7 × 15.7 (400 × 400)                                                            128     15    3.7 × 10.sup.5                       4   18.9 × 18.9 (480 × 480)                                                            64      45    1.6 × 10.sup.6                       5   14.2 × 14.2 (360 × 360)                                                            48      88    1.8 × 10.sup.6                       6   11.3 × 11.3 (288 × 288)                                                            36      195   2.5 × 10.sup.6                       7   11.8 × 23.6 (300 × 600)                                                            50      78    2.2 × 10.sup.6                       8   11.8 × 11.8 (300 × 300)                                                            50      204   2.8 × 10.sup.6                       9   15.7 × 15.7 (400 × 400)                                                            256     44    1.1 × 10.sup.6                      10   14.2 × 14.2 (360 × 360)                                                            64      67    1.3 × 10.sup. 6                     11   18.9 × 18.9 (480 × 480)                                                            128     35    1.4 × 10.sup.6                      Comparative Examples:                                                          1   9.4 × 9.4 (240 × 240)                                                              32      120   1.1 × 10.sup.6                       2   14.2 × 14.2 (360 × 360)                                                            48      203   4.1 × 10.sup.6                       3   15.7 × 15.7 (400 × 400)                                                            128     11    2.7 × 10.sup.5                       4   7.1 × 7.1 (180 × 180)                                                              24      102   5.1 × 10.sup.5                      ______________________________________                                         .sup.*1 DPI = Dots/inch                                                       .sup.*2 The volume of ink ejected from one nozzle according to one signal     .sup.*3 The amount of ink adhered in solid image recording.              

                  TABLE 2                                                         ______________________________________                                        Optical                                                                       density  Dry time (sec)       Overall                                         (OD)     15° C., 80% RH                                                                      20° C., 55% RH                                                                     evaluation                                  ______________________________________                                        Examples:                                                                      2   1.1     37           24        4.1                                        3   0.9     31           20        3.9                                        4   1.2     31           26        4.3                                        5   1.3     45           36        4.4                                        6   1.6     54           44        4.0                                        7   1.4     42           30        4.1                                        8   0.9     <5           <5        4.0                                        9   1.4     35           20        4.4                                       10   1.5     27           15        4.3                                       11   1.5     33           26        4.5                                       Comparative Examples:                                                          1   0.8     50           41        3.1                                        2   1.6     143          115       2.4                                        3   0.5     37           22        1.9                                        4   0.7     73           46        2.1                                       ______________________________________                                    

As described above, the present invention can provide good images withsuperior ink fixing performance and optical density of images which arealso free from feathering, even when ordinary paper is used in highdensity recording.

We claim:
 1. A multi-nozzle ink-jet recording process comprising thesteps of:ejecting ink droplets; and adhering said ink droplets on arecording medium at a recording density of at least 100 dots/mm² and3.0×10⁶ pl/cm².
 2. The ink-jet recording process of claim 1, whereinsaid recording process is an on-demand system.
 3. The ink-jet recordingprocess of claim 1, wherein said recording density is at most 576dots/mm².
 4. The ink-jet recording process of claim 2, wherein saidrecording density is at least 196 dots/mm².
 5. The ink-jet recordingprocess of claim 1, wherein said ink is adhered in an amount rangingbetween 5.0×10⁵ pl/cm² and 2.5×10⁶ pl/cm².
 6. The ink-jet recordingprocess of claim 1, wherein said ink is adhered in an amount rangingbetween 1.0×10⁶ pl/cm² and 2.0×10⁶ pl/cm².
 7. The ink-jet recordingprocess of claim 1, wherein said ink contains a colorant in the range of0.5 to 10% by weight.
 8. The ink-jet recording process of claim 1,wherein said recording medium is a sheet of paper having a basis weightranging between 45 and 200 g/m².
 9. A multi-nozzle ink-jet recordingprocess comprising the steps of:ejecting ink droplets; and adhering saidink droplets on a recording medium at a recording density of at least196 dots/mm², in an amount ranging between 1.0×10⁶ and 2.0 ×10⁶ pl/cm².10. The ink-jet recording process of claim 9, wherein said recordingprocess is an on-demand system.
 11. The ink-jet recording process ofclaim 9, wherein said recording density is at most 576 dots/mm².
 12. Theink-jet recording process of claim 9, wherein said ink contains acolorant in the range of 0.5 to 10% by weight.
 13. The ink-jet recordingprocess of claim 9, wherein said recording medium is a sheet of paperhaving a basis weight ranging between 45 and 200 g/m².
 14. Amulti-nozzle ink-jet recording process comprising the steps of:selectingan ink containing 1 to 45% by weight of an organic solvent having aboiling point of at least 150° C.; ejecting droplets of said ink; andadhering said ink droplets on a recording medium at a recording densityof at least 100 dots/mm² in an amount ranging between 3.0×10⁵ and3.0×10⁶ pl/cm².
 15. The ink-jet recording process of claim 14, whereinsaid recording density is at most 576 dots/mm².
 16. The ink-jetrecording process of claim 15, wherein said recording density is atleast 196 dots/mm².
 17. The ink-jet recording process of claim 14,wherein said ink is adhered in an amount ranging between 5.0×10⁵ pl/cm²and 2.5×10⁶ pl/cm².
 18. The ink-jet recording process of claim 14,wherein said ink is adhered in an amount ranging between 1.0×10⁶ pl/cm²and 2.0×10⁶ pl/cm².
 19. The ink-jet recording process of claim 14,wherein said ink contains a colorant in the range of 0.5 to 10% byweight.
 20. The ink-jet recording process of claim 14, wherein saidrecording medium is a sheet of paper having a basis weight rangingbetween 45 and 200 g/m².
 21. A multi-nozzle ink-jet recording processcomprising the steps of:selecting an ink containing 1 to 45% by weightof an organic solvent having a boiling point of at least 150° C.;ejecting droplets of said ink; and adhering said ink droplets on arecording medium at a recording density of at least 196 dots/mm² in anamount ranging between 1.0×10⁶ and 2.0×10⁶ pl/cm².
 22. The ink-jetrecording process of claim 21, wherein said recording density is at most576 dots/mm².
 23. The ink-jet recording process of claim 21, whereinsaid ink contains a colorant in the range of 0.5 to 10% by weight. 24.The ink-jet recording process of claim 21, wherein said recording mediumis a sheet of paper having a basis weight ranging between 45 and 200g/m².
 25. The ink-jet recording process of claim 23, wherein saidrecording process is an on-demand system.
 26. The ink-jet recordingprocess of claim 20, wherein said recording process is an on-demandsystem.
 27. A multi-nozzle ink-jet recording process for forming a colorimage with inks of different colors, which comprises the stepsof:ejecting droplets of said inks of different colors; and adhering saidink droplets on a recording medium at a recording density of at least100 dots/mm² in an amount ranging between 3.0×10⁵ and 3.0×10⁶ pl/cm².28. The ink-jet process of claim 27, wherein said recording process isan on-demand system.
 29. The ink-jet process of claim 28, wherein saidrecording density is at most 576 dots/mm².
 30. The ink-jet process ofclaim 29, wherein said recording density is at least 196 dots/mm². 31.The ink-jet recording process of claim 27, wherein said inks are adheredin an amount ranging between 5.0×10⁵ and 2.5×10⁶ pl/cm².
 32. The ink-jetrecording process of claim 30, wherein said inks are adhered in anamount ranging between 1.0×10⁶ and 2.0×10⁶ pl/cm².
 33. The ink-jetrecording process of claim 28, wherein said inks each contain a colorantin the range of 0.5 to 10% by weight.
 34. The ink-jet recording processof claim 33, wherein said recording medium is a sheet of paper having abasis weight ranging between 45 and 200 g/m².